Telephone system



A. E. LUNDELL. TELEPHONE SYSTEM.

APPLICATION FILED DEC.30, I916- Patented Aug. 9, 1921.

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TELEPHONE SYSTEM. APPLICATION FILED nmao, 191's.

Pawnted Aug. 9', 1921.

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TELEPHONE SYSTEM.

APPLICATION FILED -DEC.30, 1916.

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A IiEBEN E. LUNDELL, OI NEHYORK, N111, ASSIGNOE"TO"WESTERN ELECTRIC COM- rm, mconronmnn, or NEW firemen. Y., A oonrommon or NEW YORK.

rnmrfionn SYSTEM.

, matic telephone systems.

In systems ofthis type, the calling subscriber on removing his receiver from the switchhook, actuates a line signal which 1ncates to an operator that a call has or1g1- nated on this line. The operator then inserts her answering plug into the calling jack and ascertains from the subscriber the number of the desired line. The operator there-.

upon makes a memorandum of the number of the desired line andthen depresses the keys of a sending and controlling device I viate the necessity ofthe operators written;

which controls the setting of automatic switches in connecting the, calling with the called subscribed.

- It is the purpose of this invention to obmemorandum and to increase the facility with which she sets up a connection.

The main feature of this invention is the provision of means to indicate to the calling station the number of the called line associated with a particular connecting unit.

Another feature of this invention is the provision oiimeans wherebythe operator may again cause the indication ofthe number of the called subscriber at any time after the listening sequence switch has passed out of the listening-in position, and before the called subscriber has answered. 7

Another feature of this invention is the method of establishing a connection between a calling subscriber on a partyline and another subscriber on the same party line.

The drawings, with Figure 2 placed below Fi 1 and with Figs. 3 and 4uplaoed at the rig t of Fig. 2 in the order named, diagram matically illustrate a portion of a telephone system employing the present invention.

Fig. 4 shows a plurality of telegraphones which-are arranged to be connected to the operators head set under the. control of a sending device.

The switches employed in the system are of the power type in which the brush shaft Specification of Letters Patent.

Patented Aug. 9, 1921.

Application filed December 30,1216. SeriaI No. 139,936.

This system also employs sequence switches I of the type disclosedin Patent No. 1,127,808

to Reynolds and Baldwin. The contacts of each sequence switch are separated from the contacts of the other sequence switches employed, by dotted lines, and by the confines of the drawings. Each sequence switch is provided with a master contact indicated in the drawings above the clutch magnet of the sequence switch. This master contact is open in the stop positions of the sequence switch indicated by the numerals'placed adjacent to these contacts. In the other posi tions of the sequence. switch, this master contact is closed to ground and thereby c'ompletes an operating circuit for the sequence switch. A plurality of registers, which are herein designated as the hundredstens and 'units registers, may be of the same structure as the sequence switches above mentioned.

A series of counting relays arranged'to be controlled in part by these registers, is also employed. The complete actuating circuits for the counting relays and the operation of the same are fully disclosed in Patent No. 1,168,319 to Lundelh It is believed that the operation of the present invention will best be understood by establishing a connection from a calling substation A to a called substation which is indicated at B. When the calling subscriber removes his receiver from the switchhook, aline relay 122 is actuated to close a local circuit for the lighting of lamp signal 123. As soon as the lamp signal-123 is lighted, it indicates to "the operator that a call has originated on that line- The operator then inserts the answering plug 124 into the calling jack 125. This completes a circuit from grounded battery, winding of relay 126," sleeveof plug 124:, sleeve of jack 125, winding of cut-oil relay 127, to ground. Relays 126 and 127 are-energized. The energization of'cut-ofi' "clay, 127 serves to disconnect the line relay 122 from the calling line and this operationin turn extinguishes lamp signal 123. As'soon as. the relay 126 attracts its armature, a circuit is completed to move 'the'listening-in sequence switch 106 from grounded battery, magnet of sequence switch 105, contact 104 (1), front contact and armature of relay 126, to ground. Sequence switch 105 continues to rotate by reason of the circuit completed through its master contact 167 until it reaches position 7.

As soon as the listening-in sequence switch 105 moves out of position 1, a circuit is prepared for moving the sequence switch 100 out of position 1. This circuit extends from grounded battery, magnet of sequence switch 100, conductor 128, contact 103 (1), contact 104 (2 to 7), front contact and armature of relay 126, to ground.

)Vhen the sequence switch 100 reaches position 2, a circuit is closed to move the cord finder sequence switch 200 out of position 1. This circuit extends from grounded battery, magnet of sequence switch 200, contact 201 (1), brush 264, conductor 202, contact 108 (7), contact 112 (2), to ground. In position 2 of the cord finder sequence switch 200, a' circuit is completed for the up-drive magnet 203 from grounded battery, winding of magnet 203, contact 204 (2),, right-hand back contact and armature of relay 205, to ground. As soon as the brushes of the cord finder have associated an idle sending device with the cord circuit to which the calling line has been connected, the relay 205 is energized over the following circuiti grounded battery, winding ofrelay 205,'c.ontact 206 (2), brush 235, conductor 207, contact 108 (7), contact 112 (2), to ground. The relay 205 attracts its armatures. At its righthand armature and back contact it interrupts the operating circuit of the up-drive magnet, and at its le t-hand armature and front contact it completes a locking circuit for itself, which is maintained closed until the district sequence switch 100 moves out of position 11. This locking circuit may be traced from grounded battery, winding of magnet'205, contact 206 (2 to 17), front contact and armature ofrelay 205, brush 236, conductor 208, contact 129 (2 to 11), to ground. At this time sequence'switch 200 is moved out of position 2.

In position 7 A of the listening-in sequence switch 105, the operators head set generallydesignated as 148 is telephonically connected to the calling subscribers substation A, through the contacts 110 (6 to 8) and 111 (6 to 8). The operator, ,u on ascertaining the number of the wante subscriber,depresses the keys of a controlling device indi-- cated in Fig. 3 of the-drawings. Let it be' 5 assumed that'the operator sets up the numher 921. After the operator has depressed thehundreds, tens and units keys corresponding to the number 921, she depresses a start key 303,"whereupon the hundreds register 304, the tens register 305, and the units register 306 are rotated to the stop positions indicated by the depressed keys 300, 301 and 302 respectively. I The operating circuit of the register 304 extends from grounded battery, magnet of register 304, right-hand armature and back contact of stop relay 307, conductor 308, start key 303, to ground. The operating circuit for the tens register 305 is similarly traced through the back contact and right-hand armature of stop relay 309, toground, and the operating circuit for the units register 305 is likewise traced through thefback contact of stop relay 310. As soon. as these registers reach stop positions indicated by the depressed keys, stop relays 307, 309 and 310 are energized-in the well-known manner to interrupt the operating circuit of these registers. The energizing circuit for. stop relay 307 may be traced from grounded battery, winding of relay 307,

switch 200 continues to rotate until it reaches position 9, by reason of a circuit completed through its master contact 210. While the.

sequence switch 200 is moving through positions 4 00.8, contact 265 completes a circuit for energizing the key-releasing relays 319.

When the sequence switch-200 rotates through position 4, an energizing circuit for line relay 130 is completed from grounded I battery, winding of relay 130, contact 120 (2), conductor 146, brush 257, contact 234 (4 to 9), to ground. The line relay 130 attracts its armatures and at its right-hand armature completes a circuit from ground,

right-hand armature and front contact of relay 130, contact 121 ,(2), conductor 132, magnet ofsequence switch 100, to grounded battery, to move this sequence switch out of position 2. i

In position 96f the cord finder sequence switch 200, while sequence switch 100 was in position-2, the fundamental circuit is established from grounded battery, winding of relay 130, contacti' 120. (2), conductor 131, brush 237, outer armature and back contact of the'upper zero counting relay 213-, winding of stepping relay 214, contact 215 (9), brush 239, conductor-.216, contacts 118 (2 to 3 ),-to ground.

In position 3 of the sequence switch 100 a locking circuit is completed for the relay 130. This circuit extends from grounded battery, winding of relay 130, left-hand front contact and armature of this relay. contact 120 to 3), then over the fimdamental circuit prevlously In position 3 of the sequence switch 100 an energizing circuit is also provided for the updrive magnet 139 to operate the selector switch 138. This circuit extends from grounded battery, winding of magnet 139, contact 119 right-hand front contact and armature of relay 130 to ground. As the commutator brush 136 engages conducting portion 134 of commutator 135 when the selector switch is being elevated, a circuit in shunt of the fundamental circuit is also completed from grounded battery, winding of relay 130, left-hand front contact and armature of this relay, contact 120 (2 to 3), conductor 133, conducting portion 134 of commutator 135, commutator brush 136 to ground.

In order to simplify the present disclosure, it has been assumed that the selector switch 138 has one directive movement and a hunting movement, and it has also been assumed that the connector indicated bythe wipers 140 and 141 has only two directive movements, one movement to select the group and the second movement to select the'desired line in the group.

In position 9 of sequence switch 200 a contact 211 is closed to complete a circuit to actuate the first of a chain of counting relays corresponding to the hundreds digit of the desired number, as determined by the setting of the hundreds register 304. As the commutator brush 136 carried by the selector brush-rod encounters a conducting segment of commutator 134 when the wipers of the selector switch are elevated over the groups of lines, the stepping relay 214 is shunted to actuate a pair of counting relays in the well-known manner. When the upper zero counting relay 213 of the chain of counting relays is energized it attracts its armatures, and at itsouter armature and back contact interrupts the fundamental circuit above described.

At the inner armature and front contact of relay 213, a circuit is closed to move the sequence switch. 200 out of position 9 This circuit is established from grounded battery, magnet of sequence switch 200, front contact and inner armature of relay 213, contact 217 (9), to ground. Sequence switch 200 continues to rotate until it reaches position 11 by reason of a circuit completed through. its master contact 210. As soon as the fundamental circuit is interrupted at the upper zero counting relay 213 when the brushes of the selector are properly centered on a selected trunlg'the line relay 130 deenergizes. At its right-hand front contact and armature the circuit of the up-drive magnet is interrupted ,to stop the selector switch in operative relation to the selected group of trunks. Trunk-hunting then takes place in the well-known manner. At the right-hand armature and back contact of relay 130, a circuit is completed from ground through contact 121 conductor 132, magnet of sequence switch 100 to grounded battery, to move sequence switch 100 out of position 3. This sequence switch continues to rotate until it reachesposition 11, in which position the fundamental circuit is extendedthrough contacts 116 (11) and 147 (11) to the succeeding switch, which in this instance is a connector switch. In position 11 of the sequence switch 200, the first of a chain of counting relays corresponding to the tens digit of the desired number is actuated in the manner above indicated. In. response to the tens impulses, brushes 140 and 141 of a connector switch are moved to select a group in which the desired line terminates. At. the close of the tens series of impulses, the zero counting relay 213 is again energized to interrupt the fundamental circuit and move the sequence switch 200 out of position 11 into position 13. This circuit extends from grounded battery, magnet of sequence switch 200, front contact and inner armature of relay 213, contact 217 (11) to ground. In position 13 the units series of impulses is transmitted to place the brushes 140 and 141 into engagement with the terminals of the selected line. At the close of the units series of impulses, the upper zero counting relay is again energized to move the sequence switch 200 out of position 13. The sequence switch 200 continues to rotate until it reaches position 15, by reason of an operating circuit completed through its master contact 210.

As soon as the sequence switch 200 reaches position-15, a circuit is completed for moving'the sequence switch 100 out of posltion 11 into position 14. This circuit may be traced from grounded battery, magnet of sequence switch 100, contact 103 (11), conductor 149. brush 240, contact 241 (15), to ground. hen the sequence switch 100 moves out of position 11, a locking circuit for the relay 205 is interrupted at contact 129, which is closed through positions 2 to 11. Upon the deenergization of the relay 205, a circuit is completed from, grounded battery, magnet of sequence switch 200, contact 201 (3 to 15), righthand back contact and armature ofrelay 205 to ground, to move the sequence switch into position 16. If the called line is idle, the removal of the receiver at the called substation causes the supervisory relay to be attracted in the wellknown manner. When relay 154 attracts its armature a circuit is completed to move the sequence switch 100 out of position 14 into position 16. This circuit may be traced from grounded battery, magnet of sequence switch 100, conductor 128, contact 109 (11 to-15), contact 114 (14), front contact and armature of relay 154, resistance, to ground.

In positions 12 to 16 of the sequence switch 100, contacts 116 and 147 are closed to extend the calling line through to the connector switch.

In the present system means are provided to restore the cord finder to its normal position if the called line is idle, but if this line is busy, the sender is held in its actuated position until the connection is severed by removal of plug 124 from the calling jack or until wipe-out key 181 is depressed. This means comprises a constantly rotating shaft 242 on which there are secured disks 243, 244 and 245. Disk 243 is formed of Y conducting material and its surface is provided with insulated portions so that a circuit extending therethrough is intermittently interrupted. The disks 244 and 245 are similarly formed of conducting material, but their peripheries, except conducting portions 246 and 247, are covered with insulating material. It should be noted here that the conducting portion 246 of disk 244 is so positioned with respect to the conducting portion 247 of disk 245, that the circuit extending through disk 244 is completed, and then interrupted before the circuit extending through the disk 245 is completed.

In case the called line is idle, and the called party answers, the supervisory relay 154 is actuated and attracts its armature.

A circuit is thereupon completed from grounded battery, resistance 155, contact 114 (15 to 16), front contact and armature of relay 154, contact 102 (16), conductor 156, brush 250, winding of relay 251, brush 252, conducting portion 246 of disk 244, to ground. The relay 251 attracts its armatures and at its front contact and righthand armature establishes a locking circuit for itself over that portion of the circuit, previously described,'by way of the armature and front. contact of the supervisory relay to grounded battery. At the left-hand front contact and armature of relay 251, a circuit is completed from grounded battery, ma net of sequence switch 200, contact 209 (16 left-hand front contact. and armature of relay 251, brush 253, conducting portion 247 of disk 245, to ground. This circuit operates to move the sequence switch 200 into position 17. In position 17 of the se uence switch 200 a circuit is completed for t e down-drive magnet 254 to restore the cord finder. This circuit .may be traced from grounded battery, magnet 254, contact 255 (17), to ground. As soon as the cord finder has returned 'to its normal position,.

a circuit is completed from grounded battery, magnet of sequence switch 200, contact 201 (17), contact 256, to ground, to move the sequence switch out of position 17. Sequence switch 200 under the control of its master contact 201, moves into position 1 or its normal position.

If the desired line is busy the connector line, a circuit is closed from grounded battery, through the repeating coil, winding of supervisory relay 154, contact 116 (12 to 16), wiper 158 of selector switch 138, terminal 159, contact 157 (17), conductor 160, brush 258, conducting portion of disk 243, to ground. The numerous insulated portionsof the disk 243 make and break the circuit just described to cause the relay 154 to vibrate its armature. As a result of the vibration of the armature of relay 154, the supervisory lamp 162 is caused to flash, thereby informing the operator that the called line is busy. In this instance, however, the relay 251 does not operate to move the sequence switch 200 out of position 16,

the circuits through disks 243 and 244 is such that the brush 252 is not in engagement with the conducting segment 246 at the same time that the relay 154 has attracted its armature. Inthis case, the cord finder sequence switch 200 will not be moved out of position 16, until the contact 163 is closed in 18 after the operator has severed the connection either by removing plug 124 from jack 125 or by the depression of a key 181 at the operators position.

In accordance with the present invention means are provided to indicate to the secondary calling station, which for illustration is shown as the operators position, the number of the called line associated with a particular connecting unit. This informasince the timing of the makes and breaks in tion is desirable whether the called line is eled gears 408, 409 and 410 at their lower ends which are driven by a constantly rotating line shaft 411, operated by a motor 412,.or other source of power. 404 carries a cam disk 413 which engages a star wheel 414. The star wheel is mounted The shaft on a rod 415 which carries an eccentrically mounted disk 416. The disk 416 is intermittently rotated .under the control of the star wheel 414, and the cam disk 413. As the wheel 416 rotates it intermittently makes and breaks contact between the spring 401 and contact 417. Various numdesignating the subscribers lines. An elec-- tromagnet similar to the ones indicated at 418, 420 and 422 is associated with each number disk to operate as described in the above mentioned patent.

At the time when the operator depresses her key 149, the sequence switch 217 is moved out of position 1 through an operatlng circuit extending from grounded battery, magnet of sequence switch 217, contact 218, 1), conductor 219, brush 220, conductor 221, contact 106 (7), key 149 to ground. Sequence switch 217 continues to rotate until-it reaches position 3, in which position an energizing circuit is completed for the relay 222 from grounded battery, winding of relay 222, contact 223 (3 to 10), conductor 224, contact 417 and spring 401 to ground. When the relay 222 attracts its armature, a circuit is completed to move the sequence switch 217 out of position 3 into position 4. This circuit extends from grounded battery, magnet of sequence switch 217, contact 218 (3), front contact and armature of relay 222 to ground. The

energizing circuit of relay 222 is inter-v rupted when spring 401 moves out of engagement with contact- 417 under the control of the eccentrically mounted disk 416 Relay 222 retracts its armature. This prt pares a circuit to move sequence switch 21'} out of position 4, which circuit may be traced from grounded battery, magnet of sequence switch 217, contact 218 (4), back contact and armature of relay 222 to ground. When the relay 222 is again energized, a circuit is completed through its front contact and armature 'for sequence switch 217 to move it into position 5. a As soon as the sequence switch 217.reaches position 5, a circuit is closed from ground, contact 225 (5 to 10), conductor 226, winding ofrelay 142 to grounded battery. Relay 142 attracts its armatures. This completes a circuitv from the operators' receiver .175, condenser 144, lower armature and.

front contact of relay 142, conductor 143,

winding of repeating coils 227, conductor 228, front contact andupper armature of relay 142, winding of induction coil 145, to the operators receiver. This circuit remains closed until the sequence switch 217 passes out of position 10. In position 6 of the sequence switch 217, a circuit is completed to transmit the number ofthe hundreds digit to the connecting operator; This circuit may be traced from repeating coils 229, contact 230 (6), conductor 2 31, contact 313 (9), conductor 314, windingof electromagnet 420,- conductor 421, to repeating coils 229. As the disk 407 rotates, it will'induce a current into the windingof electromagnet 420. Current is induced in repeating coils 227 and 229 to actuate the connecting operators receiver to indicate the number 9. On the denergization of relay 222, the sequence switch 217 is advanced to position 7 When, now, the spring 401 rengages contact 417, the relay 222 is energized. This relay attracts its armature and at its front contact completes a circuit to move the sequence switch 217 out of position 7 and into position 8. In position'8 the tens digit of the, called subscribers number is transmitted to the connecting operator. The tens digit in this instance is 2, and a circuit will therefore be completed from the repeating coils 229, contact 230 (8), conductor 232, contact 315 (2), conductor 316, Winding of electromagnet. 422', conductors 423 and 421 to the repeating coils 229. When, now, the relay 222 is deenergized, a circuit is closed at its armature and back contact to move the sequence switch 217 out of position 8-and into position;9. In position 9 a'circuit is completed to communicate the'units digit. of'the desired number which, in this case, is No. 1. A circuit is completed from the repeating (coils 229,

contact 230 (9),conductor', 233, contact 317 (1), conductor 318, a" winding of electro- -magnet 418, conductors 423 and 421 to the epeating coils 229. When the operator has ascertained the number of the line to which the calling line has been extended she depresses the listening-out key. 107, whereupon the sequence switch 105 rotates to position 11.

At the close of the conversation, when the calling or called party replaces the receiver on its 'switchhook, the supervisory relays 154 and 168 operate in the well-known manner to indicate to the operator that the call is terminated. The operator thereupon removes'plug 124' from jack 125. The sleeve relay 126 has its energizing circuit interrupted and retracts its armature. A circult is completed from grounded battery, mag- ,net of sequence-switch 105,169 (11), armathe sequence switch a circuit is completed for the downdrive magnet 170, which circuit may be traced from downdrive magnet 170, contact 118 (18) to ground. When the selector switch 138 has restoredits wipers to their normal position grounded battery,

7 mal position.

a circuit is completed from ground, commutator brush 136, conducting segments 171,

conductor 172, contact 1 21 (18), conductor 132, magnet of sequence switch 100 to grounded battery, to move the sequence switch 100 into its normal position. As soon as the sequence switch 100 is in position 18,

"a circuit is completed from ground, contact switch.

'Let us assume that the call is a revertive call, that is, a call from the substation .indicated at A to the substation indicated at A In this case when the calling subscriber A removes his receiver from its switchhook, the lamp 169 is lighted to indicate to the operator that a call has originated on this 'line. The operator thereupon inserts plug 124 into jack 170. She then depresses a listening-in key to' place her telephone set into communication with the substation at A. .She thenascertains the number of the desired line and sets up this number on a key set. As a result of the depression of the keys in 'the operators key set,the selector switch places its brushes 137 and 158 into engagement with the terminals 172, 17 3 and 174 leading to a connector switch, whose brushes are indicated at 175,176 and 177.

This connector switch in turn is .operated in accordance with the setting of the operators key set to engage the terminals 178, 179 and 180 which are individual to the party line. In this case the called line will test busy and transmit a busy-back signal to the operator in the well-known manner. To ascertain whether the call is arevertive call, the operator depresses key 166 to move the listening-in sequence switch 105 into position '1. This circuit ma be traced from grounded battery, magnet 0 sequence switch 105, contact 161 (11), key 166 to ground. In position 1 of the sequence switch 105, a circuit is completed for moving this sequence switch into a listening-in position or position 7. This circuit extends from grounded battery, magnet of sequence switch 105, contact 104 (1), front contact and armature of relay 126 toground. The operator then depresses key 149', whereupon the number indicating device operates in the manner indicated to repeat the number of the desired line to the operator. She thereupon compares this: number with the number plate that is associated with the jack 170 of the calling line. In order to complete connection between the substation A and the substation A the switching devices are no longer necessary. The operator then depresses the wipe-out key 181 to restore the switches in a manner to be indicated. As soon as the operator depresses the wipe-out key 181, a circuit is completed through contact 182 (7), contact 183 (2 to 18)., winding of relay 184, to grounded battery. Relay 184 attracts its armature and at its left-hand armature and front contact completes a circuit from ground through contact 183 (2 to 18), winding of relay 184, to grounded battery. At the right-hand armature and front contact of relay 184, a circuit is completed from ground through contact 103 (2 to 17), conductor 128, magnet of sequence switch 100, to grounded battery, to move this sequence switch into position 18. In position 18 the downdrive magnet 17 0 operates in the well-known manner to restore the selector switch and this selector switch in restoring, causes the restoration of the succeeding switches employed in establishing a connection. When the selector switch is restored to its normal position, the circuit previously described is completed through commutator brush 136 and segment 171, for moving the sequence switch 100 into position 1. In position 1 of sequence switch 100 the locking circuit of relay 184 is interrupted at contact 184, and an operating circuit is completed for moving the sequence switch 100 in position 2.

This circuit extends from grounded battery, magnet of sequence switch 100, conductor 12s, contact 103 (1), contact 107 (2 to 7),

front contact and armature of relay 126 to 100 ground. After depressing the wipe-out key 181, the operator depresses thelistening-out key. 107 and'thereby completes a circuit from ground, contact 185 (7), magnet of sequence switch 105, to grounded battery, to move the 105 sequence switch 105 into a listening-out position. With sequence switch in posi- 1 tion 2- and sequence switch in position 11, the relay 184 is energized over a circuit circuit for moving sequence switch 100 into position 1. This sequence switch remains in this position, since its driving circuit is broken at contact 104 (2 to 7).

The operator thereupon depresses one of the keys 186 and 187 to apply the proper 12 ringing current'to operate the call bell of the desired subscribers substation.

The talking battery is supplied through the windings of the repeating coil 188, plug 124 and jack 170."

What is claimed is: 1. In a telephone system, a plurality of telephone lines, a connecting circuit and an automatic switch for interconnecting said lines, an audible indicating device therefor, 130- completed through contact 182v (11) and con- 110 a register for registering the number'of'the called line and for determining the setting of said automatic switch, said indicating device operating in accordance with the number set up on'the register, and means operated at will under the control of the operator for repeating said number on said indicating device.

2. In a telephone system, a plurality of telephone lines, connecting circuits and automatic switches for interconnecting said lines, an audible indicating device common to a plurality of said connecting circuits, a register for recording the number of the called line and for determining the setting of said automatic switches, said indicating device operating in accordance with the number set up on the register, and a key actuated at will by the operator for indicating said number on said indicating device.

3. In atelephone system, a plurality of telephone lines, connecting circuits for interconnecting said lines, multiposition automatic switches individual to said connecting ister, said indicating device operating in'accordance with the'number set up on said register for indicating said number, when the 'SWltChfOI' a connecting circuit taken for use is in a predetermined position, and means under the control of the operator for restori-ng said switch to a predetermined position.

4. In a telephone system, a calling line, a plurality of called lines, means including automatic switches for interconnecting said calling'linewith any of'said called lines, a register for registering the number of the called line and for determining the setting of said automaticswitches, an audible indi-' cating device operating in accordance with the number set up on the. register, and means operated at will under the control ofuthe operator for causing said indicating deviceto repeat the number of the called line. In witness whereof, I hereunto subscribe my name this 29th day of December A. 'D.,

- ALBEN E.-L UNDELL. 

